1. Field of the Invention
This invention is directed to processes for treating effluent by-product streams containing ammonia and/or ammonium containing salts (e.g. ammonium sulfate) and undesirable by-products. In one aspect such processes are used to treat effluent by-product streams from acetonitrile, caprolactam, or acrylonitrile manufacturing processes. In one aspect of such processes a vertical tube reactor is used with an oxygen injector on a coil tubing system to remove undesirable organic contaminants from an effluent.
2. Description of Related Art
By-products generated during the manufacturing of acetonitrile or acrylonitrile are generally classified as Resource Conservation and Recovery Act (RCRA) hazardous materials. These by-products are listed as K011, K013, and K014 hazardous wastes, if they are discarded, and, as waste, are reportable under the Emergency Planning and Right-to-Know Act (EPRKA) of 1986.
K011 and K013 wastewaters include nearly all of the RCRA hazardous process waste that is generated from the manufacture of acrylonitrile. K011 wastewater is high strength and contains high concentrations of dissolved solids, primarily ammonium sulfate and significant concentrations of organic components that are difficult to treat by most conventional methods used in the chemical processing industry. K011 organic components foul heat exchanger surfaces when heated, and the wastewater is toxic to biological systems. K013 wastewater is typically lower strength, contains fewer dissolved solids, and exhibits less biological toxicity.
In one integrated prior art process K011 wastewater is pre-treated by wet oxidation to destroy the majority of the waste's organic components. The oxidation reduces the waste strength and destroys some of the components which inhibit biological treatment. The wet oxidation effluent is then processed through an evaporator/crystallizer system to remove ammonium sulfate. The ammonium sulfate is discharged from the system as crystalline product or concentration brine depending on the intended final use. Condensate from the evaporator/crystallizer is mixed with the K013 wastewater and the mixture treated in a biophysical PACT (TM) treatment system. The PACT treatment system, which combines carbon adsorption with biological assimilation, produces an effluent in an effort to satisfy RCRA or NPDES discharge requirements. The process attempts to generate low amounts of residuals for disposal and to reduce or eliminate the need for deep well disposal.
Other industrial processes also produce effluent waste streams that contain significant quantities of potentially recoverable ammonia or ammonium sulfate. One other such manufacturing process involves the production of caprolactam. Currently, these waste streams are considered to have no commercial value and are typically discarded in a manner similar to that described above for acrylonitrile production. The high volume at which all of these streams are generated (e.g. more than 300 gallons per minute) and the toxicity of the stream make treatment by conventional technologies untenable.
In certain prior art deep well oxidation units, oxygen is introduced through an oxygen inlet tube into a high temperature and pressure region of a deep well reactor. Over time (in some cases in only several hours) these tubes become corroded and oxidized and they are eventually replaced.
In certain other prior art deep well oxidation units, the oxygen inlet tube is fixed at a predetermined depth within the reactor, permitting no adjustability of tube depth and inhibiting control of the reaction zone in the reactor. Also, having a fixed tube limits the ability to modify the oxidizing zone as the composition of the stream to be processed changes and, therefore, limits the destruction efficiency of organic chemicals in the stream.
As a reactor of a deep well oxidation unit ages, so also does a downcomer tube used in such reactors, due to corrosion and resulting in a shortening in length. As the reactor ages scale and sludge accumulate in the bottom of the reactor, resulting in undesirable narrowing of the clearance between the bottom of the reactor and the oxygen inlet tube.